SOIL EROSION

Introduction to Soil Erosion

“Soil erosion is the natural process in which the topsoil of a field is carried away by physical sources
such as wind and water.”

What is soil Erosion?

Definition

It is a process in which the top fertile layer of soil is lost. Due to soil erosion, the soil becomes less fertile.
The top layer of soil is very light which is easily carried away by wind and water. The removal of topsoil by
the natural forces is known as soil erosion.

Explanation

Soil erosion is a natural process where the top layer of soil is worn away by factors like wind, water,
or human activities. Imagine a scenario where rain falls on bare soil; the force of the raindrops can
detach soil particles, and the flowing water can carry them away. Similarly, strong winds can pick up
and transport loose soil.

This erosion process can have significant effects on the land. It can lead to the loss of fertile topsoil,
which is crucial for plant growth. When topsoil is eroded, it not only affects agriculture but also
impacts the health of ecosystems. Additionally, sediment carried away by water can end up in rivers
and lakes, affecting water quality and aquatic habitats.

Human activities like deforestation, improper land use, and overgrazing can accelerate soil erosion.
To prevent or control soil erosion, various conservation methods, such as planting cover crops,
building terraces, and using retaining walls, can be implemented. These measures help to protect the
soil and maintain its fertility for sustainable land use.

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Causes of Soil Erosion

Rainfall and Flooding

Higher intensity of rainstorms is the main cause of soil erosion. Four types of soil erosion are caused
by rainfall:

 Rill erosion
 Gully erosion
 Sheet erosion
 Splash erosion
The raindrops disperse the soil, which is then washed away into the nearby streams and rivers.
Regions with very heavy and frequent rainfall face a large amount of soil loss. The flowing water
during floods also erodes a lot of soil by creating potholes, rock-cut basins, etc.

Agriculture

The farming practices are the major cause of soil erosion. The agricultural activities disturb the
ground. The trees are cleared and the land is ploughed to sow new seeds. Since most of the crops
are grown during the spring season, the land lies fallow during winters. Most of the soil is eroded
during winters.

Also, the tyres of tractors make grooves on the land, making a natural pathway for water. Fine soil
particles are eroded by wind.

Grazing

The grazing animals feed on the grasses and remove the vegetation from the land. Their hooves
churn up the soil. They also pull-out plants by their roots. This loosens the soil and makes it more
prone to erosion.

Logging and Mining

A large number of trees are cut down to carry out the logging process. Trees hold the soil firmly. The
canopy of the trees protects the soil from heavy rainfall. The leaf litter that protects the soil from
erosion, is also lost during logging.

Mining activities also disturb the land and leave the soil more prone to erosion.

Construction

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The construction of roads and buildings exposes the soil to erosion. The forests and grasslands are
cleared for construction purposes, which exposes the soil making it vulnerable to erosion.

Rivers and Streams

The flowing rivers and streams carry away the soil particles leading to a V-shaped erosion activity.

Heavy Winds

During dry weather or in the semi-arid regions, the minute soil particles are carried away by the
wind to faraway lands. This degrades the soil and results in desertification.

Types of Soil Erosion

Water erosion
Queensland’s high intensity summer rainfalls represent a significant risk of erosion by water.

Raindrops hit bare soil with enough force to break the soil aggregates. These fragments wash into
soil pores and prevent water from infiltrating the soil. Water then accumulates on the surface and
increases runoff which takes soil with it.

Well-structured soils are less prone to break up, and the impact of raindrops is minimised if the soil
surface is protected by plant or litter cover. The vulnerability of soils to water erosion depends on:

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  rainfall intensity (erosivity)—high intensity rainfall creates serious risk as heavy drops on bare
soil causes the soil surface to seal
 nature of the soil (erodibility)—clay soils vary in their ability to withstand raindrop impact
 slope length—if a slope is long, water running down the slope becomes deeper and moves
faster, taking more soil with it
 slope steepness—the speed of runoff increases on steep slopes, which increases the power
of water to break off and carry soil particles.

The main types of soil erosion by water are bank, sheet, rill, gully and splash ones.

Wind erosion
Wind erosion is a significant problem in the arid grazing lands of inland Queensland.

It is most likely to occur when strong winds blow over light-textured soils that have been heavily
grazed during drought periods.

It contributes to scalding, a process that forms smooth, bare areas on impermeable subsoils.

These areas, which vary from a few square metres to hundreds of hectares, are difficult to
revegetate due to:

 lack of topsoil
 low permeability
 their often-saline surface.

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Generally, wind erosion is not a serious issue in cropping areas. Most soils cultivated in Queensland
have a heavy texture—forming relatively large aggregates that are too coarse to be carried by strong
winds.

However, sandy soils are vulnerable to wind erosion because they cannot store very much moisture
and have low fertility. This limits their use in Queensland, with only small areas (where irrigation is
available) being cultivated for horticulture or growing vegetables.

Effects of Soil Erosion

Loss of Arable Land

Soil erosion removes the top fertile layer of the soil. This layer is rich in the essential nutrients
required by the plants and the soil. The degraded soil does not support crop production and leads to
low crop productivity.

Clogging of Waterways

The agricultural soil contains pesticides, insecticides, fertilizers, and several other chemicals. This
pollutes the water bodies where the soil flows.

The sediments accumulate in the water and raise the water levels resulting in flooding.

Air Pollution

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The dust particles merge in the air, resulting in air pollution. Some of the toxic substances such as
pesticides and petroleum can be extremely hazardous when inhaled. The dust plumes from the arid
and semi-arid regions cause widespread pollution when the winds move.

Desertification

Soil erosion is a major factor for desertification. It transforms the habitable regions into deserts.
Deforestation and destructive use of land worsens the situation. This also leads to loss of
biodiversity, degradation of the soil, and alteration in the ecosystem.

Destruction of Infrastructure

The accumulation of soil sediments in dams and along the banks can reduce their efficiency. Thus, it
affects infrastructural projects such as dams, embankments, and drainage.

Soil Conservation

Soil conservation is the set of practices and methods implemented to prevent soil degradation and
preserve the quality and fertility of soil. The primary objectives of soil conservation are to minimize
soil erosion, maintain soil structure, and promote sustainable land use. This involves the adoption of
various techniques and strategies, such as contour plowing, terracing, cover cropping, and
sustainable agriculture practices, to safeguard the soil from erosion caused by natural forces like
wind and water, as well as human activities. The goal is to ensure the long-term productivity of the
land while mitigating the adverse environmental effects associated with soil degradation.

Soil Conservation Techniques

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CONSERVATION TILLAGE

Conservation tillage consists of a variety of practices used in agriculture to reduce wind and water
erosion. The main principles are:
a) to keep bare soil protected at all times of the year either with living vegetation, or
with residue from the previous crop; and
b) to minimize the number of times the field is tilled.
Bare soil is highly susceptible to erosion. Excess tillage destroys soil structure and organic matter.
In conservation tillage, at least 20 to 30 percent of the soil surface is covered in the previous year's
crop residue after planting. The residue reduces wind velocity at the soil surface and breaks the
impact of raindrops. Root systems hold the soil in place. If practiced across a slope, rows of stubble
act as small dams to slow water as it runs downhill.
CONTOUR FARMING
Contour farming involves tilling and planting along the contour, rather than up and down the slope.
The furrows and rows of plants act as dams which slow down the flow of water moving down the
slope. Unless some type of contour farming is used, particularly on long slopes, serious field erosion
can result.
Contour farming also uses less fuel and power for tractors.

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STRIP CROPPING
Strip cropping involves alternating strips of small grain (e.g. rye) or forage crops (e.g. clover) with
row crops like corn. It is used to control erosion by reducing the velocity of wind and water. The
forage and cereal grain rows tend to trap sediment that may otherwise end up in watercourses.
Strip cropping is most effective in controlling erosion on a slope when it is placed along the contour
of the land. To control wind erosion, it works best if the strips are placed at right angles to the
direction of the prevailing winds.
Another benefit of strip cropping is the organic matter added from the forage or cereal crop rows.
WINDBREAKS
A windbreak or shelterbelt is a vegetation barrier designed to reduce or eliminate the velocity of the
wind and hence reduce wind erosion. (Windbreaks are also used for snow control and to provide
shelter for buildings and livestock).
A distinction can be made between windbreaks and shelter belts. Windbreaks consist of one to five
rows of trees or shrubs; shelter belts are six or more rows wide.
Windbreaks are generally planted on the west, southwest, or northwest boundary of a field to
provide protection from prevailing winds. The protection is maximized downwind of the barrier,
where the wind speed is significantly reduced for a distance of 15 to 20 times the height of the trees.
The windward side of the break receives protection for 3 to 5 times the total height.
The benefits of both windbreaks and shelter belts extend far beyond just erosion control. Crop
quality and livestock performance are improved due to less abrasion from blowing soil. Tree and
shrub rows significantly increase the aesthetics of the landscape which is proven by higher land
values. They also trap snow in the winter and thus provide a higher moisture content for the growing
season.

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A major benefit of windbreaks is their enhancement of wildlife habitat. They provide places to roost,
nest and seek cover from predators from harsh winter climate. The damage some animals do to
crops is balanced by the role others play in controlling insects or unwanted rodents like mice.
CROP ROTATION
Crop Rotation is an alternative to planting a field in the same crop year after year (referred to
as continuous mono-shelterbelts culture cropping). Instead, the main crop is rotated, ideally with
cereal crops like winter wheat or forages such as clover and alfalfa.
Crop rotation provides several benefits. Rotation reduces the risk of insect and disease problems,
thus decreasing a pesticide dependency. Because the crop is changed each year, pests do not have
enough time to become established in damaging numbers.
Forage crops or legumes such as clover and alfalfa are often used as green fertilizers or plow-down
crops, meaning they are planted and later mixed in with the soil as a natural fertilizer and soil
builder. Legumes have the special ability to take in atmospheric nitrogen and convert it to forms
usable by other plants. (Atmospheric nitrogen is not in a form available to most plants). For this
reason, they are also referred to as nitrogen fixing plants.
When used as a green fertilizer, legumes return a significant amount of organic matter to the soil.
Their deep roots create tunnels for air and water to enter the soil. All these characteristics in turn
guard the surface against water and wind erosion.
COVER CROPS

Cover crops are crops planted to reduce the impact of wind and water on bare soil. They absorb the
impact of rain, reduce the speed of runoff, hold the soil in place, and encourage greater infiltration;
and hence less runoff.

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Sweet clover, alfalfa, rye, and winter wheat are common cover crops. They are planted on areas
susceptible to erosion like steep slopes; stream and river banks, grassed waterways or around wells
to protect ground water supplies from contamination. Winter wheat or rye are often planted to
provide cover over the winter and 95 to 100 percent erosion control during the spring runoff.
Intercropping involves mixing plants in a field - for example planting legumes between rows of corn
or soybean. This technique may be used by a farmer who cannot afford to take his or her entire crop
of corn out of production.

Key Points of Soil Erosion

 It is the natural process of wearing away topsoil, but human activities have accelerated
the process.
 It is usually caused due to the removal of vegetation, or any activity that renders the
ground dry.
 Farming, grazing, mining, construction and recreational activities are some of the causes
of soil erosion.
 The effects of soil erosion are not just land degradation. It has led to a drastic increase in
pollution and sedimentation in rivers that clogs the water bodies resulting in a decline in
the population of aquatic organisms.
 Degraded lands lose the water holding capacity resulting in floods.
Summary

Soil erosion is a natural process where the fertile top layer of soil is carried away by physical forces
like wind and water. This erosion, caused by factors such as heavy rainfall, agricultural practices,
grazing, logging, mining, construction, rivers, and winds, has detrimental effects on the land.

There are two primary types of soil erosion: water erosion, influenced by factors like rainfall
intensity and slope characteristics, and wind erosion, a significant issue in arid grazing lands. The
consequences of soil erosion include the loss of arable land, waterway pollution, air pollution,
desertification, and damage to infrastructure.
Recognizing the importance of preserving soil quality, soil conservation methods are crucial. These
include conservation tillage, contour farming, strip cropping, windbreaks, crop rotation, and cover
crops. The aim of soil conservation is to minimize soil erosion, maintain soil structure, and ensure
sustainable land use. By adopting these techniques, we can protect the soil from degradation and
promote a healthier environment for agriculture and ecosystems.

Bibliography
https://byjus.com/biology/soil-erosion/

https://www.johnstonnc.com/swc/content.cfm?pageid=wisc

https://www.nature.com/articles/s41467-017-02142-7#:~:text=Our%20findings%20indicate%20a%20potential,estimates%20of%20soil%20erosion%20rates.

https://www.qld.gov.au/environment/land/management/soil/erosion/types\

Submitted By:
Name - Sachleen Kaur
Course – BCom. (Hons.)
Roll No. – 149
College Name – Hindu College

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